Multi piston power pack unit for fluid actuated tool

ABSTRACT

This disclosure is directed to a multi piston, double acting, fluid actuated power pack to power various tools between an operative and inoperative position to attain maximum power with limited displacement of the operating piston. This is attained by a power pack comprising of a housing partitioned to define a plurality of piston chambers and having a piston head reciprocally disposed in each of the chambers. The piston heads are connected to a piston rod which is activated between extended and retracted position as fluid pressure is exerted on the piston heads. Control means in the form of a valve and associated passages are operatively connected to the respective piston chambers for directing the flow of fluid pressure to and from the respective chambers in a manner wherein fluid pressure is applied to each of the piston heads on the power stroke, and on only at least one of the piston heads on the return stroke.

United States Patent [191 Pawloski et al.

[ Aug. 14, 1973 MULTl PISTON POWER PACK UNIT FOR Primary Examiner-Irwin C. Cohen FLUID ACTUATED TOOL Attorney-Arthur T. Fattibene [76] Inventors: James A. Pawloski, Rt. 97, PO. Box

13, North Woodstock, Conn.; 57 Grahame F. Williams 801 South St., Southbridge, Mass. This disclosure is directed to a multi piston, double actmg, fluid actuated power pack to power various tools [22] Flled: 1971 between an operative and inoperative position to attain [21 APPL NW 22 maximum power with limited displacement of the operating piston. This is attained by a power pack comprising of a housing partitioned to define a plurality of pis- [52] US. Cl. 91/411 A, 91/466, 92/1 10, ton chambers and having a piston head reciprocally d 92/151 posed in each of the chambers. The piston heads are [51] Int. Cl. FlSb 11/16, Flb 13/06 connected to a piston rod which is activated between [58] Field of Search 91/466, 41 l A; extended and retracted i i as fluid pressure i 137/625-668; 92/151, 110, 108 erted on the piston heads. Control means in the form of a valve and associated passages are operatively con- [56] References Cmd nected to the respective piston chambers for directing UNITED STATES PATENTS the flow of fluid pressure to and from the respective 360,594 4/1887 lde l37/625.68 chambers in a manner wherein fluid Pressure is pp 2,354,841 8/1944 Shaff 91/41 I A to each of the piston heads on the power stroke, and on 3,221,770 12/1965 Faisandier l37/625.68 X only at least one of the piston heads on the return 3,269,223 8/1966 Pawloski 91/466 X t ke, 3,485,141 12/1969 Ott et a] 91/41! A 1 Claim, 3 wing Figures g M h6A I95 I88 I O 5'] 3 I v M .I0 I6A 28 Z ,0 k f |Ei g7 38 ,raufzrgiVI/Il/I/l/ p mu. -52: 7 i I t a 12 5010A Em 1, 21B/ 12 I I 2 Mr 3/ $3 I w I I I U 14 19 20 [I6 55 w (I! as Patented Aug. 14, 1973 3,752,040

2 Sheets-Sheet 1 I N V[ N TOPS JA MES A. PA WLOS/f/ By GRAHAME W/LL/ANS Patented Aug. 14, 1973 Q 3,752,040

2 Sheets-Sheet 3 JAMES A. PAWLOSK/ By 15 1 E W/LL/A M5 ATTORNEY MULTI PISTON POWER PACK UNIT FOR FLUID ACTUATED TOOL PROBLEM AND PRIOR ART Heretofore, multiple piston, fluid activated power systems for operating various tools were known in which a spring return was utilized to bias or return the pistons to inoperative position. Other power systems utilized a double acting power system in which fluid pressure was alternately directed to either side of the piston to effect the operation of such tools. Generally such fluid activated systems required the use of two fluid supply lines and/or external bleed systems to evacuate the piston chambers as fluid pressure was on one side of the piston. Each of these prior known systems included inherent disadvantages which are desired to be obviated by this invention.

OBJECTS It is therefore an object of this invention to provide an improved multiple piston, double acting, fluid actuated power pack having an internally disposed bleed system for the double acting pressure chamber.

Another object is to provide a multiple piston power pack in which each of the respective pistons is subjected to fluid pressure on the power stroke to provide for maximum power and in which only one of the multiple pistons is subjected to fluid pressure on the return stroke.

Another object is to provide a multiple piston power pack in which the chambers not subjected to a double acting fluid pressure are vented directly to atmosphere.

Another object of this invention is to provide a multiple piston power pack with a double acting pressure chamber having an internal fluid supply and exhaust system controlled by a valve for directing the flow of fluid pressure to and from the double acting chamber portion of the pack.

Another object is to provide an improved multiple piston, double acitng fluid pressure power pack which is relatively simple in construction, can be readily fabricated, and which is positive in operation.

Another object is to provide a multiple piston, double acting, fluid operated power pack which requires the need of only one fluid pressure line.

BRIEF SUMMARY OF THE INVENTION The foregoing objects and other features and advantages of this invention are attained by a fluid actuated power pack comprising a housing which is partitioned to define a plurality of tandem disposed piston chambers. A piston head is displaceably disposed in each of the respective chambers which partition the respective chambers into complemcntal divisional portions. The respective piston heads are spatially connected to a common piston rod which is displaced between an extended and retracted position as fluid pressure is directed on the respective piston heads. The piston rod is provided with an internal bore closed at one end. A conduit which is operatively connected to a control valve is arranged to extend into the bore of the piston rod. The conduit is spatially disposed within the bore so that the space therebetween defines a first fluid passage means which is disposed in communication between the valve means and the respective piston chambers for exerting a fluid pressure on the piston heads during the power stroke. The conduit defines a second passage means arranged to communicate with only at least one of the piston chambers and the valve means.

The control valve for directing the flow of fluid to the respective chambers comprises a four-way valve having an inlet port disposed in open communication with the fluid inlet to the housing. The valve means also includes a first and second outlet port means which are suitably valved by a valving member to alternately direct fluid pressure to the respective piston chambers on the power stroke and for directing fluid pressure to at least only one of the respective piston chambers for effecting the return stroke. The arrangement is such that the conduit provides an internal bleed or exhaust for the one chamber on the power stroke. The other chambers are exhausted through a port formed in the chamber wall on the power stroke.

FEATURES A feature of this invention resides in the provision of a fluid activated, double acting power pack having a plurality of tandem disposed piston chambers in which fluid pressure is substantially simultaneously directed to each of the fluid chambers to exert pressure on each of the respective pistons therein to provide for maximum power on the power stroke, while the return stroke of the piston is effected by applying fluid pressure on at least one of the pistons.

Another feature of this invention resides in a multiple piston double acting fluid pressure power pack in which the double acting chamber thereof is exhausted by an internal bleed system through the control valve.

Another feature resides in the provision of a multiple piston fluid activated power pack having a single acting chamber operatively associated with a double acting chamber in which the single acting chambers are vented directly to atmosphere on the return stroke of the piston.

Another feature of this invention resides in a multiple piston, fluid activated power pack having a four-way control valve operatively connected to a single pressure line for controlling the operation of the pack.

Other features and advantages will become more readily apparent when considered in view of the drawings in which:

FIG. 1 is a cross sectional view of a multiple piston power pack embodying the present invention in which the parts are illustrated in the power activating or operative position.

FIG. 2 is a view similar to that of FIG. 1 but illustrating the relative position of the components parts in the return position or inoperative position.

FIG. 3 is an enlarged detail view of thevalve construction embodied in the invention as disclosed in FIGS. 1 and 2.

DETAILED DESCRIPTION Referring to the drawings there is shown in FIGS. 1 and 2 cross sectional view of a multiple piston, fluid activated, power pack unit 10 adapted for use for activating fluid activated tools, as for example, wire cutters and various other fluid activated tools. While the activating fluid for the unit 10 may comprise a liquid or hydraulic type of fluid, the illustrated form of the invention is disclosed and described as utilizing compressed air as the activating fluid medium. The multiple piston power pack 10 comprises a housing 11 in the form of a tubular body defined by opposed end walls 12 and 13 interconnected by a circumscribing wall 14 to define an interior space. In the illustrated form of the invention the rear wall 12 of the housing is preferably integrally connected with the circumscribing wall portion 14 of the housing 11. The front end wall 12 is preferably detachably secured to the open end of the housing by any suitable means, e. g. screw threads.

As best seen in FIGS. 1 and 2 the internal surface of the circumferential wall 14 of the housing is provided with an internal shoulder 16 intermediate the ends to define an abutment against which a partitioning member 17 is seated for partitioning the housing 11 into a plurality of distinct piston chambers 18 and 19. As shown, the partition member 17 comprises an annular member having a central opening 17A and it is retained in abutting position against the internal shoulder 16 by means of a suitable retaining ring 20. It will be noted that the central opening 17A of the partition member 17 is disposed in alignment with a central opening 13A formed in the front end wall 13. The respective openings 13A and 17A define a bearing for the piston rod 21 of a piston means adapted to be disposed within the housing 11.

The piston means, as shown, comprises the piston rod 21 which is adapted to extend through the aligned openings 13A and 17A which are circumscribed by suitable sealing means in the form of O-rings 22 and 23. Connected in spaced relationship on the piston rod 21 are piston heads 24 and 25 which are adapted to be displaceably disposed in the respective piston chambers 18 and 19. Accordingly, the respective piston heads 24 and 25 partition their respective piston chambers 18, 19 into complementary expandible divisional portions 18A, 18B and 19A, 198.

In the illustrated embodiment the piston rod is preferably formed of two connected sections 21A and 218 which are threadedly coupled at 21C. Also if desired, piston head 24 may be integrally formed with piston rod portion 218. The forward end of piston rod portion 21B is provided with a shoulder 21D against which piston head 25 abuts. The piston head 25 is maintained in shoulder 21D by an end flange 21E formed on piston rod 21A when the latter is screw threaded to piston rod portion 21B.

As best seen in FIGS. 1 and 2 the piston rod 21 is provided with an internal longitudinally extending bore 27 which is closed at one end as at 28. Adapted to be received within bore 27 is a conduit 29 which is fixed to and extends inwardly from the rear wall 12 of the housing 11 in substantially spaced, concentric relationship to the bore 27. The arrangement is such that the external diameter of the conduit 29 is less than the internal diameter of bore 27, thereby defining an annular space 30 therebetween. Adjacent the extended end of the conduit 29, the annular space 30 is sealed off by a suitable sealing ring 31. As will be hereinafter described the annular space 30 defines a portion ofa first passage means which is arranged to be disposed in communication with the corresponding divisional portions 18A and 19A of the respective piston chambers 18 and 19. As best seen in FIGS. 1 and 2 the open end of sapce 30 is in communication with divisional portion 18A of piston chamber 18 and a port opening 33 formed in the piston rod 21B effects the communication between the annular passageway 30 and the divisional portion 19A of the front piston chamber 19. Port opening 34 is formed in the piston rod 21 ahead of piston head 25 for connecting the complementary divisional portion 19B of piston chamber 19 with a second passage means extending through the conduit 29.

The control means for controlling the flow of fluid pressure to the respective piston chamber 18, 19 comprises a valve means 35 which is interposed in the rear wall portion 12 of the housing 11. As shown, the rear wall 12 of the housing is provided with a valve chamber 36 in the form of a bore formed therein. Formed in the end wall 12 of the housing is a fluid inlet 37 to which a pressure line 38, adapted to connect to a source of fluid pressure, e.g. compressed air, is detachably coupled thereto.

The valve means comprises a valve body 39 in the form of a cup-shaped member and is press fitted in the valve chamber 36. As best seen in FIG. 3, the valve body 39 is provided with an inlet port 40 which is disposed in communication with the fluid inlet 37. The valve body is provided with upper and lower circumscribing grooves 41 and 42 which communicate with a first and second port means 43 and 44. Ports 43 are adapted to communicate the fluid inlet 40 with the second passage means as will be hereinafter described, and ports 44 are adapted to communicate fluid inlet 40 with the first passage means 30. The valve body 39 also comprises an internal bore 45 which is adapted to receive a valving member 46.

The valving member 46 comprises a valve stem 46A having spaced thereon a pair of spaced apart valving heads 47, 48 which are adapted to alternately valve the first and second port means 43, 44 for controlling the direction of flow of fluid to and from the respective piston chambers l8, 19. As best seen in FIG. 3 the valve stem 46A is provided with an internal bore 468 which is adapted to receive a valve spring 49. The valve spring 49 is such that it will normally bias the valve stem 46A upwardly as best seen in FIG. 2, wherein the valve fluid inlet 40 is disposed in communication with the central conduit 29 or second passage means so that the fluid pressure is directed to chamber portion 198 to normally maintain or bias the piston heads to their retracted or inoperative position as see in FIG. 2. Thus in the normal, inoperative position of the power pack 10, the fluid under pressure in the pressure line 38 is directed through the inlet opening 37 of the housing 1], through the inlet 40 of the valve body 39, thence through the outlet ports 43 of the valve body 39 which are disposed in communication with the second passage means or central conduit 29. From conduit 29 the pressurized fluid or compressed air is directed through the open end of the conduit and through port opening 34 into the complementary divisional portion 198 of the front piston chamber 19 to exert pressure against the piston head which normally maintains or returns the respective piston heads 24, 25 and connected piston rod 21 in their retracted or normally inoperative position.

The valve or control means 35 is activated by an operator in the form of a suitable hand lever 50 which is pivotally connected at one end by pin 51 to a bracket 52 secured to the end of the housing 11. It will be noted that the valve spring will normally bias the valve stem 46A against the lever 50 in the inoperative position. To activate the power pack 10 to impose a power stroke thereto, the operating lever is depressed toward the housing 11, thereby causing the valve stem 46A to be depressed downwardly. In doing so the displacement of the valve stem 46A causes the valve heads 47 and 48 to close the port means 43 to the valve inlet 40 and to open port means 44 to the valve inlet 40 so as to connect the complementary portions 18A, 19A to the respective piston chamber l8, 19 in communication with the pressure fluid entering the inlet 37. Accordingly the fluid under pressure is simultaneously directed directly through ports 44 to complementary divisional portion 18A of piston chamber 18, and to the divisional portion 119A of chamber 19 through passage 30 and port 33 whereby a simultaneous fluid pressure is exerted on each of the valve heads 24, 25 to effect a displacement of the piston rod to an extended or operative position under maximum fluid pressure as seen in FIG. 1. It will be noted that as long as the handle or lever 50 is maintained depressed, the piston heads and associated piston rods will be maintained in the extended or operative position as the air on the opposite side of the piston heads is exhausted. To effect the displacement of the piston heads 24, 25 within their respective piston chambers 18, 19, the complementary divisional portions 18B, 19B of the respective piston chamber 18, 19 are exhausted as will be described. In the illustrated arrangement it will be noted that the complementary divisional portion 198 of the front piston chamber 19 is exhausted through an internal bleed system defined by the second passage means which includes port 34, passageway 29 and second or port means 43 of the valve body which vents to atmosphere through an enlarged stem opening 54 formed in the housing ll. The complementary portion 188 of the chamber 18 is vented directly to atmosphere through a port 55 formed in the annular cylinder wall portion thereof. Thus, on the power stroke, the complementary portion 198 of one piston chamber, e.g. 19, is internally vented through conduit 29 through the valve stem opening 54, whereas the other complementary portion 188 of the other piston chamber 18 is vented directly to atmosphere through port 55.

To effect the return of the pistons to effect a retraction of the associated piston rod 21, the operating handie 50 is released causing the valve spring 49 to bias the valve stem 46A to its normal or inoperative position. In this position the valve heads open the second or port means 43 to the inlet 37 and close the first port means 44 to the inlet 37 so that fluid pressure is now directed from the inlet 37through the second passage means or conduit 29 and through port opening 34 to exert a pressure on the adjacent side of piston head 25. In doing so the complementary divisional portion 19A of the double acting piston 25 of the tool is vented or exhausted through port 33 and connected first passage means or space 30 through the valve ports 43, and out the stem 46 through ports 56 as indicated in FIG. 2. It will be noted that the valve stem 46A is provided with lateral port openings 56 disposed in communication with the central bore which contains the valve spring 49. Thus on the return stroke chamber portion 19A is vented through the valve stem as described. The complementary portion 18A of the other chamber 18 is also vented through the valve stem as air is induced through the port opening 55, as the piston head 24 is displaced to the right as viewed in FIG. 2.

The construction defined is directed to a relatively simple multiple piston power pack unit having a plurality of piston chambers l8, l9 suitably connected to a control valve 35 wherein pressure fluid is simultaneously imparted to each of the respective piston heads 24, 25 to provide for maximum power with a limited displacement of the associated piston rod. It will be understood that the piston rod 21 is suitably connected to a ram or actuator for effecting the operation of an appropriate tool head (not shown).

The control means 35 is constructed so that on the return stroke, fluid pressure is exerted to only one of the piston heads, e.g. 25, so that only a fractional amount of the pressure is required to return the respective piston heads.

While the present invention has been disclosed and described with respect to a power pack wherein the two piston chambers l8, 19 are shown, it will be understood that any number of piston chambers may be disposed in tandem. In the event that more than two piston chambers are disposed in tandem it will be understood that each of the single acting piston chambers is vented to the atomosphere through a port opening, e.g. port 55, formed in communication with the complementary divisional portion thereof; whereas the double acting chamber required for power return is vented through the internal bleed system described.

While the present invention has been described with respect to a particular embodiment thereof it will be readily appreciated and understood that variations and modifications may be made without departing from the spirit or scope of the invention.

We claim:

1. A fluid actuated, multi-piston power pack applicable for use with a fluid activated tool comprising:

a housing defined by opposed end walls and a connected circumscribing wall to define a compartment therein,

means partitioning said compartment into a plurality of tandem chambers,

piston means including a piston rod and a plurality of spaced piston heads connected thereto for movement therewith between an extended and retracted position,

each of said piston heads being displaceably disposed in its respective chambers and dividing the respective chambers into a pair of expandible divisions,

said piston rod extending through an opening formed in an end wall of said housing,

means defining a fluid inlet formed in the other end wall of said housing,

said piston rod having a bore therein which is closed at one end,

a conduit rigidly secured to said housing and spatially disposed within said bore to define a first annular passage in the space therebetween, said conduit opening to said bore to define a second passage nested within said first passage,

a sealing means circumscribing said conduit intennediate the length thereof to seal the first passage from said second passage,

a pair of ports formed in said piston rod,

said pair of ports being disposed so that one of said pair of ports is disposed on opposite sides of said sealing means so as to communicate the complementary divisions of one of said chambers with said first and second passages respectively,

a valving means interposed in said housing between said first and second passages and said housing inlet means,

said valving means including a valve body having a fluid inlet adapted to be disposed in communication with said housing inlet and a duct opening leading to the outside of said housing,

said valve body including a first port and a second port,

said first port being disposed in communication with said first passage, and said second port being disposed within said second passage,

21 valve member disposed in said valve body for valving said first and second ports,

said valve member including a valve stem and a pair of valve heads spaced thereon, said stem being positioned within said duct opening,

said stem having a bore extending therein,

said stem having ports formed in the upper end the bias of said spring. 

1. A fluid actuated, multi-piston power pack applicable for use with a fluid activated tool comprising: a housing defined by opposed end walls and a connected circumscribing wall to define a compartment therein, means partitioning said compartment into a plurality of tandem chambers, piston means including a piston rod and a plurality of spaced piston heads connected thereto for movement therewith between an extended and retracted position, each of said piston heads being displaceably disposed in its respective chambers and dividing the respective chambers into a pair of expandible divisions, said piston rod extending through an opening formed in an end wall of said housing, means defining a fluid inlet formed in the other end wall of said housing, said piston rod having a bore therein which is closed at one end, a conduit rigidly secured to said housing and spatially disposed within said bore to define a first annular passage in the space therebetween, said conduit opening to said bore to define a second passage nested within said first passage, a sealing means circumscribing said conduit intermediate the length thereof to seal the first passage from said second passage, a pair of ports formed in said piston rod, said pair of ports being disposed so that one of said pair of ports is disposed on opposite sides of said sealing means so as to communicate the complementary divisions of one of said chambers with said first and second passages respectively, a valving means interposed in said housing between said first and second passages and said housing inlet means, said valving means including a valve body having a fluid inlet adapted to be disposed in communication with said housing inlet and a duct opening leading to the outside of said housing, said valve body including a first port and a second port, said first port being disposed in communication with said first passage, and said second port being disposed within said second passage, a valve member disposed in said valve body for valving said first and second ports, said valve member including a valve stem and a pair of valve heads spaced thereon, said stem being positioned within said duct opening, said stem having a bore extending therein, said stem having ports formed in the upper end thereof, said stem ports venting to the atmosphere through said duct opening, said stem bore being adapted to be disposed in communication with said first passage for said one chamber in the return stroke of said pistons, a spring disposed in the bore of said stem to normally bias said stem toward an inoperative position, and a port formed on the wall of the other piston chamber to vent said other chamber to atmosphere, and a valve handle abutting the end of said valve stem to effect displacement of said valve stem against the bias of said spring. 